With domestic market buckling under the pressure of the global financial crisis, the country's top 10 firms suffered a loss of over Rs 1 trillion in a week, led by state-run oil major ONGC [Get Quote] which lost for Rs 22,000 crore (Rs 220 billion) in market valuation.

The combined market capitalisation of the country's top 10 firms saw an erosion of Rs 1.23 lakh crore (Rs 1.23 trillion) in the past week, dropping to Rs 11,38,734 crore (Rs 11,387.34 billion) from the previous week's Rs 12,61,788 crore (Rs 12,617.88 billion).

PSU refiner ONGC lost Rs 22,191 crore (Rs 221.91 billion) last week, the highest fall among the top 10 firms, which fell to Rs 1,95,888 crore (Rs 1,958.88 billion) at the end of trade on October 10 last week.

The country's most valued firm, Reliance Industries [Get Quote] retained its numero uno position despite a loss of Rs 15,680 crore (Rs 156.80 billion) during the past week. The market valuation of the Mukesh Ambani-led firm declined to Rs 2,40,318 crore (Rs 2403.18 billion) last week.

Besides, the top 10 firms underwent a change in their rankings last week, with NTPC replacing telecom major Bharti Airtel [Get Quote] at the third place, while State Bank of India [Get Quote] moved ahead of MMTC to the fifth rank.

The meltdown in the market, saw state-run power utility NTPC losing over Rs 5,000 crore (Rs 50 billion) in its market cap of Rs 1,36,503 crore (Rs 1365.03 billion) and Bharti Airtel fell to the fourth place with a drop of over Rs 12,300 crore (Rs 123 billion).